1. Field of the Invention
The invention relates to the oil field industry. More particularly, the invention relates to hydrocarbon production systems in highly deviated (&gt;55.degree. deviation) wellbores.
2. Prior Art
Highly deviated or horizontally disposed wellbores have been employed in growing numbers in recent years to access oil reservoirs not previously realistically productible. In an open hole completion however, and especially where there is water closely below the oil layer or gas closely above, highly deviated or horizontal wells are much more difficult to produce.
Pressure drop produced at the surface to extract oil from the formation is as its highest at the heel of the highly deviated or horizontal well. In an open hole well, this causes water or gas coning and early breakthrough at the heel of (or any part of) the highly deviated or horizontal well. Such a breakthrough is a serious impediment to hydrocarbon recovery because once water has broken through, all production from the highly deviated or horizontal is contaminated in prior art systems. Contaminated oil is either forsaken or separated at the surface. Although separation methods and apparatuses have become very effective they still add expense to the production operation. Contamination always was and still remains undesirable.
Another inherent drawback to open hole highly deviated or horizontal wells is that if there is no mechanism to filter the sand or formation solids prior to being swept up the production tubing, a large amount of solids is conveyed through the production equipment effectively sand blasting and damaging the same. A consequent problem is that the borehole will continue to become larger as sand is pumped out. Cave-ins are common and over time the sand immediately surrounding the production tubing will plug off and necessitate some kind of remediation. This generally occurs before the well has been significantly depleted.
To overcome this latter problem the art has known to gravel (gravel being used according to the vernacular; gravel, sand, and similar particulate matter) pack the highly deviated or horizontal open hole wells to filter out the sand and support the bore hole. As will be recognized by one of skill in the art, a gravel packing operation generally comprises running a screen in the hole and then pumping gravel therearound in known ways. While the gravel (such as gravel, ceramic beads, sand etc.) effectively alleviates the latter identified drawbacks, water or gas coning and breakthrough are not alleviated and the highly deviated or horizontal well may still be effectively occluded by a water breakthrough.
To achieve zonal isolation, the art has known to gravel pack multiple stages between pre-activated isolation devices (such as external casing packers (ECP) etc.). This operation is known to be complex, time consuming and at high risk.
Since prior attempts at enhancing productivity in highly deviated or horizontal wellbores have not been entirely successful, the art is still in need of a system capable of reliably and substantially controlling, monitoring and enhancing production from open hole highly deviated or horizontal wellbores.